1. Field of the Invention
This invention relates to a method for imaging a sphere disposition in a planer lens and the like constructed in such a way that a plurality of transparent spheres, for example, are disposed in a single layer in a substantially plane shape, a method and an apparatus for measuring the same, and a method and an apparatus for manufacturing the planer lens.
2. Description of the Related Art
For example, some translucent screens for rear projectors (translucent or rear projection projectors) are of such a construction that a large number of transparent spheres such as glass beads are two-dimensionally disposed in a single layer and the spaces among them are filled with light absorption materials (e.g., U.S. Pat. Nos. 2,378,252 and 3,552,822, and Japanese Published Unexamined Patent Application No. Hei 3-31727, etc.).
By using such a planer lens, there can be obtained a high-performance screen which has wide viewing angles both in horizontal and vertical directions.
With such a planer lens, to improve performance attributes such as screen penetration factor, it is important that transparent spheres are disposed as densely as possible.
For example, there are disclosed in Japanese Published Unexamined Patent Application No. Hei 9-15660 a method and apparatus for dispersing a large number of minute spheres on an adhesive layer and pressing them from top by a pressure roller so as to be embedded in the adhesive layer and disposed in high density.
In the process of manufacturing such a planer lens, however, only persons have been conventionally available to observe and check the disposition of the transparent spheres and the degree of the filling. This has resulted in an increase in labor costs, leading to higher manufacturing costs.